As well as being the definitive man's man, Dave Mackay was the indestructible hero in the movies who leaves his enemies shouting, "What does it take to kill this goddamn sunnabitch?" as bullets, knives and sharply worded insults bounce off him. Mackay was definitely one of the good guys: a genuinely outstanding left-half and a truly honourable man, who used his clout to put the hurt on opponents but never - never - to seriously hurt them. Nonetheless he was intimidating enough to send the opposition, psychologically, for an early bath. And engaging him aggressively was not to be advised. Bruce Banner had nothing on Mackay.

Billy Bremner discovered this when he kicked Mackay's bad leg. The picture of Mackay, teeth gritted so hard that it seems like they're about to splinter everywhere, grabbing a terrified Bremner by the shirt was football's most iconic hard-man photo until thespian shithouse Vinnie Jones tried to get blood out of Paul Gascoigne's stones.

Mackay could show anger, but never - never - pain. Not because, like Steve Waugh for example, he thought it showed weakness to the opposition, but because the part of his brain that registered pain or fear had apparently stopped working. After he suffered a grotesque leg-break at Old Trafford in 1963, which would keep him out for almost two years, he barely grimaced, and as he was stretchered off he sat up leaning on his elbow, looking almost bored. Truly, types come no stronger, or silent.

Billy's Boots was one of the most evocative examples of football's capacity for romance and fairytale. Billy's boot, which went in many a time on helpless defenders, was one of the most provocative examples of football's mundane, crippling reality. And his elbows weren't especially congenial either.

Mick Harford, all dead eyes and slumbering menace, was the anti-poster boy for a generation of nails-hard centre-forwards to be forever viewed through claret-tinted spectacles, but Whitehurst, a journeyman striker described by Alan Hansen as the hardest man he played against, would give him a serious run for his money. Some might surmise that Whitehurst was the unprepossessing evocation of a mercifully bygone age of wanton thuggery. Others would simply say that he was an utter bastard.

Nobody would deny that he was seriously hard. He once apparently offered out the entire Crystal Palace side in the players' lounge at Hull. When he was at Oxford, he was rumoured to be supplementing his weekly pay, and winding down, with some bare-knuckle tomfoolery with local gypsies. Neil Ruddock said that, when Billy whispered sweet promises in his ear mid-match, "I used to start shaking".

Vinnie Jones, a colleague at Sheffield United, recalls in his autobiography how Billy nipped a burgeoning rumble with a phalanx of Sheffield Wednesday fans in the bud by sparking out the opposition ringleader with "one of the best right-handers I have ever seen - inside or outside a ring". During that spell at Sheffield United, he was sent out to roam the green with the explicit instructions from his manager, Dave Bassett: "Go and cause some bollocks, Billy." He so rarely disappointed.

Just as sexiness does not necessarily equate to the exposure of flesh or cheap talk about erotic jazz or rusty trombones, so hardness doesn't necessarily mean going round kicking people. It's all in the mind. What's really hard is to know that 10 blokes want to kick seven bells out of you, and to carry on as normal. With few exceptions - the most notable being when he put the studs on Batista against Brazil in 1982 - Diego Maradona did just that.

It takes superhuman courage to carry on as normal after you've suffered the most brutal ankle break at the feet of the Butcher of Bilbao, but Maradona did. He carried on knowing that his very ability and swagger made jealous opponents want to really hurt him. He carried on zig-zagging through people, knowing that at any point one of them might take a shortcut through the back of him. He carried on demanding possession at every turn, knowing it might ultimately cost him his ability to move freely in his dotage. Now that's hard. And it made for some seriously sexy football, too.

If someone punches you by surprise, it doesn't hurt that much because it's unexpected; if someone tells you they're going to punch you and then does so, it really smarts. The first example is playing football against everyone else; the second is playing football when you're being man-marked by Claudio Gentile.

With Gentile, the ultimate symbol of Italian cynicism, pain was always in the post, and usually by special delivery. He was a celebrity stalker, whose target switched every week to the opposition's best player. Gentile didn't give a flyer about the narrative of the game: his part was simply to stop his direct opponent by foul means or fouler. Nothing was off limits. He would spit in your face, or draw conclusions about your mother that even the Goldie Lookin' Chain would balk at. And if he thought you looked in urgent need of a prostate examination, well, why wait for the doctors?

It was like working alongside someone rightinyourearallthetimejusttalkingincessantlyaboutnothing. Only a lot worse. He did his most famous number on Maradona at the 1982 World Cup, with a performance that would have come close to justifying the existence of Playercam (there are bits after 2:10 of this video). But Gentile didn't discriminate: he would put as much time and effort into banjoing Peter Barnes or even Peter Purves as he would Maradona. And, without exception, they knew it was coming.

Frank Bastar- sorry, Barson was perhaps the first great hard man, an imperious specimen of masculinity notorious for his inventive take on physical contact in football in the 1920s. He certainly looked the part: thighs like tree trunks, fists permanently half-clenched, and hair greased back so tight that it came within an extra comb of terminally restricting the bloodflow. Barson could play - he once scored a header from 30 yards - but was inevitably remembered for a then unprecedented degree of disciplinary trouble.

He was banned for seven months after cleaning out a Fulham player. After one especially zesty display, he had to be smuggled out of Goodison Park to avoid a group of home fans who wanted to discuss a couple of tactical subtleties. Some stories suggest he brought a gun into the manager's office to accelerate discussions over a pay rise. And he unashamedly spoke of his friendship with the Fowler brothers, who were later hanged for murder. Puts a new spin on Gazza wolfing kebabs with Chris Evans and Danny Baker, doesn't it?

Before football became a non-contact sport, players frequently spoke about the first 10 minutes as a period in which you had to "earn the right to play", essentially by being hard. It was arguably even more important the other way round: you had to earn the right to be hard by showing you could play; otherwise you came across as the sort of cowardly fraud that passes for today's hard men.

To misquote David Brent: 'did Souness pass the test? He gave the test'. He was a majestic all-round midfield player, arguably the best from these shores for nearly half a century, but he was also, of course, an utter beast of a man: a Glasgow kiss made flesh. In England at the turn of the 70s/80s, he simply owned the middle third of the pitch, like a Top Trumps card with a higher score than everyone else on every category. But when the legs and, to a lesser extent, the eyes went towards the end of his career, he had to rely on an inadvertently hilarious thuggery.

On his debut as Rangers player-manager in 1986, he walked inside half an hour, after kicking a Hibs player for the heinous crime of cleanly dispossessing him (if you look carefully, Souness actually nobbles the wrong gangling mullet, an easy mistake to make in Edinburgh in the mid-80s). A year later he committed surely the most preposterous violation in the history of humanity, never mind football, on a poor Steaua Bucharest player. And if you're still in any doubt about how hard Souness was, ask yourself: can you think of anyone else who would do this?

Rob Smyth is part of a group running 10 miles (which is 9.9 more than he's ever run before) for the Laurie Engel Fund in London on August 31. To sponsor him, click here; to read why he's doing it, click here; or to join in the run, email Rob